Regarding OSRIC, I can't speak for Clark but I think I can see it like this.
The problem with OSRIC, as opposed to something like, say, C&C, is this.
C&C appears to have been started from the System Reference Document, and then tweaked it so it emulates 1e play without actually being 1e rules--such as adding back level limits, changing the XP rules, etc. There are a lot of compromises involved here. You can clearly see the path they took in developing the game.
OSRIC appears to be using the SRD as the rights to use the licensed trademarks and IP to justify creation of a 100% 1e compatible rule-set. PJ really nailed it. It doesn't look as derived from the existing SRD base, rather an attempt to reverse engineer 1e D&D fuller instead of just making a lot of variant rules for 3e.
From a legal standpoint, it could appear that they are trying to take a closed property (the 1e/2e game system), and make it open by combining the "no copyright for games" law, with the OGL's viral nature, using the SRD'd version of D&D to justify this. But since WoTC has never opened up this property, they could choose to argue this in the court. Maybe they haven't touched the "retro-clones" because they don't consider it a threat. I have a feeling the first person who releases a non-underground 4e clone and tries to use the OGL SRD to defend it is gonna get stomped.
But I can understand why Orcus and others are wary of the use of OSRIC. I think there are limits to the OGL and what the SRD can be used for.